The family grouping of the river dolphins has always been a problem. Using molecular data, both Árnason and Gullberg (1996) and Yang et al. (2002) found no direct relationship between Platanista and the other river dolphins. Messenger and McGuire (1998) generated a phylogenetic tree supporting the idea that river dolphins are not monophyletic. In a recent retroposon analysis of the major cetacean lineages the authors found that platanistid dolphins, beaked whales and ocean dolphins diverged (in this order) after sperm whales (Nikaido et al. 2001). Within the other river dolphins the other three genera were found to form a monophyletic group. Hamilton (et al. 2001), based on cytochrome b, also supports Platanista in a separate family. The only remaining disagreement is the placement of the other three genera. Yang et al. (2002) and Rice (1998) placed Lipotes in a separate family and Rice (1998:92-95) placed all three of the other genera in separate families as well. At the present time we favor a two family arrangement, with Platanista in the family Platanistidae and the other three genera in the family Iniidae.